1. Field of the Invention
The present invention generally relates to systems and methods for treating water. More particularly, the invention relates to the reduction of contaminants from wastewater using bacteria.
2. Description of the Relevant Art
Domestic wastewater contains various physical, chemical and bacteriological constituents, which require treatment prior to release to the environment. Various wastewater treatment processes exist which provide for the reduction of oxygen demanding materials, suspended solids and pathogenic organisms. Reduction of nutrients, principally phosphorous and nitrogen, has been practiced primarily since the 1960's at treatment plants where there is a specific need for nutrient reduction to protect the water quality and, hence, the uses of the receiving waters, whether ground water or surface water. The primary reasons for nutrient reduction are to protect water quality for drinking water purposes, as there is a drinking water standard for nitrite and nitrate, and to reduce the potential for eutrophication in nutrient sensitive surface waters by the reduction of nitrogen and/or phosphorus.
Fluidized bed bioreactors have been used to treat wastewater. In a fluidized bed bioreactor, granular media containing bacteria may be positioned in a water column and fluidization may be obtained by liquid recirculation or by external gas fed into the bioreactor. During use a biomass forms on the granular media. Wastewater may be processed through the bioreactor by contacting the wastewater with the biomass. Alternatively, an activated sludge from operational wastewater treatment systems may be used to form a biofloc or biomass. The formation of a biofloc or biomass from the sludge may be time consuming and may not allow customization for specific wastewater contaminants. In addition, as bacteria in a biofloc or biomass fall off of the mass and/or die, a system to replenish specific strains of bacteria in the biofloc may not exist.
Improvements to existing bioreactors are desirable to improve the efficiency and longevity of biological water treatment systems.